Conventionally, resin beads have been used in various fields, such as a matting agent, a lubricant, and an antiblocking agent, because of the characteristics originating in the spherical shape. Furthermore, various kinds of resin powders (resin particles) have been used as makeup application in cosmetic materials in order to improve extensibility. However, these resin powders are liable to bleed due to water or sweat, thus there is a problem that makeup deterioration occurs when such bleed occurs, and when the resin powders are utilized in cosmetic materials, modification of the resin powders, or other methods has been conducted in order to maintain the adherence to skin, or other purposes.
As a method of modifying a resin powder, there is, for example, a method of applying hydrophobization treatment to a resin powder to improve the adherence to skin. As the method of applying hydrophobization treatment to a resin powder, a method of applying heat treatment with an oil agent to the surface of a powder, a method of baking a methyl hydrogen polysiloxane onto a powder, and so on are known. Furthermore, a proposal has been made on a powder the surface of which is coated with, for example, a silicone-acrylic-based graft copolymer in order to obtain a cosmetic material that achieves a higher functionality, that is excellent in adherence to skin and in feeling after use, that is rich in hydrophobicity, and that has a favorable persistence of makeup (see, Patent Literature 1).
Moreover, there is also a method of improving the adherence to skin by making a resin powder porous. As the method of making a resin powder porous, there is a method in which an oil phase containing a monomer and an organic solvent is subjected to suspension polymerization in an aqueous medium, and thereafter the organic solvent is distilled to obtain porous resin particles, and a proposal has been made to increase the oil absorption and improve persistence of makeup by making the resin particles porous in the manner as described above (see Patent Literature 2).
Moreover, in Patent Literature 3, it is described that, even though imparting water repellency, improving adherence to skin or the like, and securing compatibility with a coexisting oil agent are simultaneously required for silicone polymers that are often used in cosmetic materials, hydrophilicity is lost by introducing a long-chain alkyl group (hydrophobic group) in a silicone polymer in order to improve compatibility, on the other hand, hydrophobicity is lost by introducing a hydrophilic group in order to improve adherence, and thus it is difficult to solve the compatibility and the adherence simultaneously. Against the problem, it is described in Patent Literature 3 that, a copolymer obtained by copolymerizing four kinds of different monomer units each containing a particular amount of a silicone macromonomer having a particular structure can impart the water repellency, and at the same time, improve the adherence to skin or the like and the persistence of makeup.